Tiered Conductive Pillar for Sensor Thermal Stress Reduction
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Solution Overview
Problem
Existing sensor devices face challenges in achieving stable detection sensitivity and reducing size while maintaining high measurement accuracy, particularly in angle sensors used for detecting orientation or rotation angles in limited spaces.
Innovation Solution
The design incorporates a support substrate, a sensor chip with a stacked structure including a sensor substrate and sensor element circuitry, and an electrically-conductive pillar with a tiered structure where a first tier part with a larger cross-sectional area is stacked on top of a second tier part with a smaller cross-sectional area, both extending through an insulating film, allowing for reduced thermal stress and increased integration density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sensor device size is reduced and integration density is increased, then the device can be used in limited spaces with higher integration, but thermal stress on the sensor element circuitry increases causing unstable detection sensitivity
Solution Approach 1:
The electrically-conductive pillar is divided into two distinct parts: a first part extending from the support substrate to the insulating film, and a second part extending from the insulating film to the sensor element circuitry. This segmentation allows each part to be optimized independently for their respective functions, reducing overall thermal stress while maintaining electrical connectivity.
Solution Approach 2:
The first part of the electrically-conductive pillar is designed with a larger cross-sectional area to handle higher current density and dissipate heat away from the sensor element circuitry, while the second part has a smaller cross-sectional area to minimize thermal stress on the sensitive sensor elements. This local quality variation optimizes thermal management at different locations.
2Ease of manufacture
If the electrically-conductive pillar has a uniform cross-sectional area, then the manufacturing process is simpler, but the thermal stress distribution is uneven causing detection sensitivity issues
Solution Approach 1:
The pillar fabrication process is segmented into two distinct formation steps: first forming the first part with a larger cross-sectional area, then forming the second part with a smaller cross-sectional area on top of the first part. This segmented approach enables precise control of thermal stress distribution while maintaining manufacturing feasibility through standard multi-step fabrication processes.
3Reliability
If the pillar height is increased to extend above the sensor chip, then electrical connectivity is improved, but the device height increases reducing miniaturization benefits
Solution Approach 1:
The electrically-conductive pillar extends primarily in the vertical dimension through the insulating film to establish electrical connectivity with the sensor element circuitry, while the tiered cross-sectional structure optimizes thermal management in the horizontal plane. This dimensional optimization allows good electrical connectivity without excessive height increase.
Data Source
AI summary
A sensor device includes a support, a sensor chip, and an electrically-conductive pillar. The support has a first surface. The sensor chip is provided on the first surface and includes a substrate and a sensor element circuitry. The substrate has a second surface. The sensor element circuitry is provided on the second surface. The electrically-conductive pillar is provided on the first surface. The electrically-conductive pillar has a pillar height from the first surface to an upper end of the electrically-conductive pillar. The sensor chip has a chip height from the first surface to the second surface. The pillar height is greater than the chip height. The electrically-conductive pillar includes a structure in which a first tier part having a first cross-sectional area and a second tier part having a second cross-sectional area smaller than the first cross-sectional area are stacked in order from the first surface.